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By R. W. Raymond

Four portraits have recently been hung in the rooms of the Institute, in recognition of four illustrious men with whom we, as mining engineers and metallurgists, may claim fellowship. Luther. Martin Luther is often spoken of as a miner's son; but it is less generally known that John Luther, his father, was, in a small way, a metallurgist as well as a miner, and that Martin Luther himself, in his youth, worked in a forge or bloomary established by his father at Mansfeld, Saxony. Since this is the only manual occupation on his part of which we have ally record, it is fair to assume that the great scholar and reformer derived from his work in this department the practical familiarity with the conditions of human labor so abundantly evinced in the homely illustrations which accompany even his serious arguments, and in the witty apothegms of his famous " table-talk." At the same time, I must confess that I have not been able to find in any of the works of Luther distinct allusions to mining or metallurgy. Körner. Theodor Körner, a student at the Mining Academy of Freiberg, Saxony, threw himself into the German War of Freedom in the first decade of the 19th Century. He was a poet of no mean rank; and his " Song of the Sword " is one of the great lyrics of literature. This poem was written but a few days before he died in battle. In many respects, Körner may be compared with our American hero Theodore Winthrop, who similarly met a glorious fate, and left behind him prophetic indications of geniue, of which his premature death prevented the complete fulfillment. I am informed by a member of the Institute that Körner's admirable collection of minerals is still preserved at Dresden.

Jan 1, 1909

By H.A. Schwartz

From time to time, one of the authors has had occasion to investigate the graphitizing reaction and has published the results mainly as discussion' of the work of other investigators. In view, therefore, of the diversity of both observations and interpretation, it seemed well to attempt, a revision of the entire subject in the Research Laboratory of the National Malleable Castings Co. The work consisted of a careful study of a single, impure, iron-carbon alloy. The material, which may be considered typical low-carbon white cast iron of the malleable industry, was an air-furnace iron of the following composit,ion: carbon 2.30 per cent., silicon 1.20 per cent., manganese 0.29 per cent., phosphorus 0.156 per cent., sulfur 0.048 per cent. The freezing range extended from 1213' to 1132' C., the latter figure agreeing with Gontermann's data.2 We have attempted to define the equilibrium diagram of this alloy, in the stable condition as related to the mctastable diagr,aui,- from a temperature somewhat below the euteetic freezing point to a temperature l>clow Arl and for a graphitic-carbon content from practically notliing to the original total rarbon of the specimen (see Fig. 6). More csp~c~ially we desired to locate the line in the stable diagra~n corrcspo~idi~lg to thc Ac, line of the metastable syst,ern, which is designated by analogy, thc At, line (t, from tcrnpcr carbon); also to dctermirle the locat'ion of A tm witah respect, to Acm t,o~vard their lowcr extremities at Arl in ordei to determine whether or not graphitization is completed by th~ separation of an iron-carbon entectoid analogous to pearlite in the iron-cementite system. This would involvc furthcr a colnparison of thc locations of Ihc stablc and met.astable 41 points. As the carbon concelltrations of thc solid solutions of the two syste~~ls are probably not, identical, an explanation of t>lieir differences and of thc,

Jan 1, 1923

By H. A. Schwartz

From time to time, one of the authors has had occasion to investigate the graphitizing reaction and has published the results mainly as discussion' of the work of other investigators. In view, therefore, of the diversity of both observations and interpretation, it seemed well to attempt, a revision of the entire subject in the Research Laboratory of the National Malleable Castings Co. The work consisted of a careful study of a single, impure, iron-carbon alloy. The material, which may be considered typical low-carbon white cast iron of the malleable industry, was an air-furnace iron of the following composit,ion: carbon 2.30 per cent., silicon 1.20 per cent., manganese 0.29 per cent., phosphorus 0.156 per cent., sulfur 0.048 per cent. The freezing range extended from 1213' to 1132' C., the latter figure agreeing with Gontermann's data.2 We have attempted to define the equilibrium diagram of this alloy, in the stable condition as related to the mctastable diagr,aui,- from a temperature somewhat below the euteetic freezing point to a temperature l>clow Arl and for a graphitic-carbon content from practically notliing to the original total rarbon of the specimen (see Fig. 6). More csp~c~ially we desired to locate the line in the stable diagra~n corrcspo~idi~lg to thc Ac, line of the metastable syst,ern, which is designated by analogy, thc At, line (t, from tcrnpcr carbon); also to dctermirle the locat'ion of A tm witah respect, to Acm t,o~vard their lowcr extremities at Arl in ordei to determine whether or not graphitization is completed by th~ separation of an iron-carbon entectoid analogous to pearlite in the iron-cementite system. This would involvc furthcr a colnparison of thc locations of Ihc stablc and met.astable 41 points. As the carbon concelltrations of thc solid solutions of the two syste~~ls are probably not, identical, an explanation of t>lieir differences and of thc,

Jan 1, 1923

A PAPER on "Iron and Steel Scrap in Blast-fur-nace Burdens," by W. C. McKee, general super-intendent, Federal Furnace plant, By-Products Coke Corp., Chicago, was published in the October issue of MINING AND METALLURGY, and written discussion by Richard Moldenke was published in the December issue. Following is the stenographic report of the oral discus-sion that took place when this paper was presented at Pittsburgh. J. N. REESE, Monessen, Pa.-I came to the conclusion that Mr. McKee must be using a poor grade of scrap, therefore his loss was high. Mr. Franchot said that there was ex-cess heat in the stack. There is no excess heat in the hearth, therefore, any heat that is used to melt this scrap must come from the stack. By using scrap in a blast furnace you can utilize this excess heat in the stack. The amount of scrap that can be used in any particular furnace involves a direct relation to the efficiency of that furnace. If a furnace is running on a very low-coke rate, you will not be able to use much; if on a high-coke rate, you can use considerable scrap, probably several times as much as that mentioned in these papers-without using any additional coke. This excess heat can be utilized with-out practically any serious mechanical and operating diffi-culties such as might be occasioned by removing gas from a point other than the top of the furnace. I do not think, scrap has any effect on the iron, although I think some foundrymen are trying to prove that it has, and perhaps some open-hearth men may have that idea.

Jan 1, 1927

US underground mine production of nonfuel minerals was 153 million tons of crude ore in 1971, according to a recent US Bureau of Mines report compiled by Dravo Corp. Underground capacity includes all nonfuel mineral commodities and is distributed into three general categories: (1) metallic ores; (2) nonmetallic ores; and (3) construction materials, such as clay, sandstone, and limestone. All three categories are produced by a combination of open-pit and underground methods. While US underground mining represents only 5.9% of total domestic capacity, it is significant in the types of products produced. Domestic supplies of potash, trona, A lead, zinc, sulfur, and fluorspar are almost exclusively recovered from underground mines, as well as a significant portion of the gold, silver, molybdenum, and salt supply.

Jan 7, 1975

By F. C. Sturges

[CONTENTS PAGE ................. Introduction-Grouting in Mines. By F. C. STURGES. I Use and Technique of Pressure Grouting in the Construction Industry. By V. L. MINEAR . 3 Technique of Pressure Cementing in the Petroleum, Mining, and Construction Industries. By WY. D. OWSLEY and R. E. MOELLER. ..................... 9 An Example of Controlled Pre-grouting in Shaft Sinking. By R. H. ALLEN and J. W. GALPIN. 15 ........ Solidifying Mines and Shafts Areas by Pressure Grouting. By B. H. MOTT 17 .............. Grouting in Southeast Missouri District. By W. W. WEIGEL 20] Introduction-Grouting in Mines By definition the word "grout" means a thin mortar, or a kind of plaster or cement, and "grouting" means to fill up or finish with grout. The words "cement," "plaster" and "mortar" mean a substance that is used in a soft state which subsequently hardens. Thus, grouting is the filling of void space with a substance that hardens. Construction cements are the most common substances used, either by themselves or in mixtures, but the term grouting is applied quite correctly when other substances such as plastics and certain chemicals are used. Also, the use of the term grouting to cover the filling of voids with materials that do not actually become hard, such as the flotation tailings used in grouting in the southeast Missouri lead district, should be considered correct, as some stiffening does take place and, anyway, it is a better descriptive term than any substitute. Engineers are interested in grouting because some of the materials with which they must work contain voids, and certain conditions can be improved if these voids can be filled with something solid and permanent. Grouting is done to accomplish several purposes: I. To stop the passage of fluids and gases, 2. To cement materials together to make them stronger, and 3. To prevent consolidation of materials by filling void space with something solid as a replacement for the air and water that could be forced out under load. The construction industry uses grouting extensively for all three purposes. Grouting is used to stop water percolation under and around dams. It is used to control water flow in tunnel driving and in shaft sinking. It is used to improve foundation conditions under civil engineering structures by permanently filling void space and thereby reducing settlement, or by cementing broken rock together and increasing its supporting strength. The oil and gas industry does a lot of grouting, primarily to stop the passage of gases and fluids. The search for oil at increasingly greater depths has meant greater investment per well, and the oil industry has spent large sums on development of improved drilling methods. This

Jan 1, 1947

By Walter L. Crow

MUCH has been published on highly technical phases of grinding. Very little has been written on how a mill man can improve his operations by determining the optimum size assortment of grinding balls that should be added as a makeup charge. This ball rationing is not to be confused with the ball ration used as an initial charge when the mill is started up. Ball rationing is considered for one or more of the following purposes: 1) to increase throughput of the mill, 2) to reduce the power required per ton of ore ground to the desired size, 3) to reduce steel consumption per ton of ore ground, 4) to improve product size, and 5) to lower retention time of ore in the mill.

Jan 7, 1957

By Kenneth Seaver

Discussion of the paper of KENNETH SEAVER, presented at the San Francisco meeting, September, 1915 and at the New York meeting, February, 1916, and printed in Bulletin No. 105, September, 1915, pp. 1913 to 1927. WILLIAM HUTTON BLAUVELT, Syracuse, N. Y.-I think that Professor Richards' statement regarding the reason for the failure of the Bethlehem ovens was due to a misconception on his part. Silica bricks were not used because the ovens were built under German design and management and it has not been the practice in Europe to use silica brick nor has it been necessary, on account of their lower heats and slower coking time as compared with the present American practice. J. W. RICHARDS, So. Bethlehem, Pa.-While acting as Chairman at the San Francisco meeting, in introducing this paper of Mr. Seaver, I made some remarks in discussion referring to unsuitable brick having been used in a coke plant at So. Bethlehem, Pa., and being the principal cause of the failure of these ovens. This statement having come to the attention of the Didier-March Co. of Perth Amboy, N. J., who furnished the firebrick used in the construction in the original ovens referred to, at the Lehigh Coke Works, near So. Bethlehem, Pa., their. manager, Geo. A. Balz has corresponded with me, and wishes to have placed on record a general denial of the statement referred to. As a matter of justice to the manufacturers of the firebrick, it is but right that their statement should be given as much publicity as my statement which has been objected to, and I take pleasure in placing upon record the statement of Mr. Balz, general manager for Didier-March Co., extracted from a letter to me dated Jan. 14, as follows: "The

Jan 5, 1916

By R. T. Mishler

I wish to express my keen appreciation of the article on the above subject by Coe and C1evenger.l It has been doubly interesting to me, for the reason that the experience recorded and the principles evolved practically parallel the results of similar investigations made by myself and others at The Lucky Tiger Mine, El Tigre, Sonora, Mex. An outline of the work at El Tigre may aid in confirming the principles expressed by Coe and Clevenger. El Tigre has the unenviable distinction of possessing a slime with a much lower settling rate than any recorded in the article discussed. Under most favorable conditions the settling rate is about one-third that reported for the Liberty Bell mill, and one-tenth that reported for the Nipissing, Golden Cycle, and Presidio mills. This slow settling characteristic of Tigre ore has necessitated careful investigation of settling phenomena throughout the various evolutions of the plant. Previous Settling Investigation at Tigre During construction work at the mill, the metallurgical engineer in charge, D. L. H. Forbes, ran a series of experiments on settling. His tests proved that deep settling tanks were not ordinarily necessary. The use of tanks 2 or 3 ft. in depth was suggested.2 Later experiments demonstrated that the following principles of settling applied to Tigre pulp.3 1. In settling dilute pulp, settling rates are independent of pulp depth. 2. In settling thick pulp, settling rates are approximately proportional to pulp depth.4

Jan 1, 1918

By T. Guilford Smith

In presenting the subject of " Armored Turrets for Coast Defense " to this Institute, I am indebted to the Gruson Ironworks, a company incorporated under the laws of the State of New York, for valuable information, model and plans, by which I hope to make clear the construction and peculiar merits of this class of gun-protection. I wish it understood, however, that this is not an undeveloped and untried inventor's ideal, but an advanced and fully perfected system, which has long since passed the experimental stage and has been adopted by most of the foreign governments, after years of extensive experimenting and the expenditure of millions of dollars. The present seems an appropriate time to present the matter to the scientific public, since, for the first time, it is possible to produce these turrets in this country, of American material, and made by American workmen, owing to an agreement entered into between the Gruson Iron-works and the Fried. Krupp Grusonwerk, of Magdeburg-Buckau, Germany, where they have hitherto alone been manufactured. Although its full development and present perfection have been attained at the German works, it may be of historic interest to state that the first idea of using a rotating protected platform for large guns originated with Mr. Theo. Ruggles Timby, a native of the State of New York, who filed a caveat in 1843 for a " metallic revolving fort, to be used on land or water, and to be revolved by propelling engines located within the same and acting upon suitable mechanism." This was followed in 1862 by the issuance to Mr. Timby of two patents (No. 35,846 and No. 36,593) covering the ideas described in his caveat of 1843. The first practical application of this system was made on the " Monitor," of Civil War fame, Mr. Timby receiving $10,000 for two

Jan 1, 1901

By Kenneth A. Moon

An exact statistical treatment of a one-dimensional model is used as a basis for evoluating the reliability of certain simplified expressions for the activity of the solute in interstitial solutions, including one obtained from the exact expression by setting the repulsive interaction equal to infinity. The latter approximation is found to be satisfactory at low and moderate concentration if the repulsive interaction is large, even though not infinite. A similar expression (identical if the co-odination number is two) is derived from the quasichemical expression of Lacher, and is recommended as the best available expression for the excess configurational entropy of interstitial solutions with excluded sites. Some reasonable models are discussed, and the nature of the saturated solutions is determined by inspection. Some of the models reduce to the one -dimensional case. An analysis is given of the excess partial entropy of hydrogen in V-H; Nb-H; and To-H solutions. MOST treatments of the statistical thermodynamics of interstitial solid solutions have followed the classic paper1 of Lacher in making the simplifying assumption that the configurational entropy of the solution is ideal. However, it is becoming increasingly apparent that there are many interstitial solutions with very large so lute-solute repulsions, and for these the assumption of ideal entropy is not valid or useful. It is important to realize that with substitutional solutions large repulsions between the component atoms must lead to phase separation, whereas in interstitial solutions the free energy of the solution is not drastically increased by large solute-solute repulsions until intrinsic saturation is reached at the concentration where further solute would be forced to enter a site in which it would experience the repulsive effect of one or more solute atoms already present. In the limiting case of an infinitely large repulsive interaction, the excess free energy would be attributable entirely to excess entropy, the enthalpy of mixing being zero. AS will be shown below, even if the repulsions are less than infinite, a treatment based on an assumption of infinite repulsions may be very satisfactory up to moderately high concentrations of the interstitial component. Often in solutions where large repulsive interactions exist, there are also small interactions — often attractive—between solute atoms in configurations other than that corresponding to the large repulsion. In such cases the excess free energy will consist of an excess entropy term attributable to the large repulsive interactions, and an enthalpy term corresponding to the other small interactions. Nomenclature to differentiate succinctly between important cases would be a convenience. In this paper the nomenclature shown in Table I will be used. In Table I, and in the preceeding discussion, excess quantities are defined in terms of standard states which are pure solid solvent and pure (possibly hypothetical) solid saturated phase of the structure in question. In practice, it is more convenient to choose the interstitial element as a component, and its conventional standard state. This will add a composition-independent term to the excess entropy and the enthalpy. The earliest paper known to the present author which treats the thermodynamics of athermal interstitial solutions was given by schei12 in 1951, but the statistical derivations in that paper are open to criticism. Speiser and Spretnak were the first to give a correct statistical treatment,3 limited, however, to concentrations sufficiently low that the number of empty sites excluded from occupancy by more than one filled site is negligible. The purpose of the present paper is to extend the statistical treatment to more concentrated solutions, and to examine the magnitude of the errors introduced by assuming that the repulsive interactions are infinite when in fact they must be finite. THE QUASICHEMICAL APPROXIMATION Fortunately, a standard method already exists for taking into account the effect of large interactions upon the entropy of mixing. This is the quasi-chemical method, in which the probability of existence of a given pair of solute atoms in a certain proximate configuration is assumed to be proportional to exp(-w/kT), where w is the energy increase of the solution when the two atoms are moved from isolated locations in the solution to the configuration in question. A quasichemical treatment of interstitial solutions was given in 1937 in a widely neglected paper by Lacher.4 The result comes out

Jan 1, 1963

By Cyril Smith

SEVERAL investigators, mainly concerned with the mechanical proper-ties of the alloys, have studied the so-called aluminum bronzes after various quenching and reheating treatments. Of these works, perhaps the most complete is that of Bouldoires,1 who studied changes of length, electrical conductivity, thermoelectric force, hardness and micro-structure oh tempering quenched alloys containing 5 to 20 per cent of aluminum, although the work of Carpenter and Edwards,2 Curry,3 Greenwood,4 Braesco,5 Matsuda;6,7 Grard8 and others has added much to our knowledge of the changes occurring during tempering. The so-called acicular ß decomposes on tempering at temperatures between 350° C. and the eutectoid, giving rise to a Widmanstätten structure of a needles in a matrix of d or fine a + d, associated with an increase in hardness and almost complete loss of ductility. Matsuda, studied the' eutectoid transformation by means of dilatation and electrical "conductivity measurements during cooling at different rates. He found that on cooling at the rate of 10° C. per minute there was a decrease in electrical resistance and in length instead of the usual increase which occurred with slow rates of cooling. On tempering the rapidly cooled samples, the increase commenced at about 400° C. and at 520° C. the resistance and length had reached the equilibrium values. These peculiarities he accounted for as being due to a transitional phase ß' being formed, ß having an electrical resistance and volume less than either ß or a + d.

Jan 1, 1933

By George Holderer

THE Enos Coal Mining Co. owns an area underlaid by coal, of approximately 5000 acres. This property is situated 9 miles from Oakland City, in the southern part of Indiana. The mine has been in operation 5 years, during which time some 350 acres have been stripped, and stripping is now proceeding at the rate of about 100 acres per year. TOPOGRAPHY These coal lands consist of gently-rolling agricultural fields which in times past were farmed for wheat. There is no timber and but very little brush to contend with. The overburden varies from 10 to 60 ft. in depth. A thin bed of slate overlies the coal, followed by limestone, which varies from 3 to 15 ft.; this, in turn, is followed by sandstone, slate, shale and clay. There is a very wide variation in the thickness of all of these beds. The coal has an average thickness of 5 ft., and is a good grade of high-volatile bituminous. MINING OPERATIONS Briefly, the sequence of operations is: drilling holes with churn drills; blasting with L. 0. X.; stripping overburden to, uncover coal and, finally taking up the coal, which is sent to a tipple for cleaning and sizing. In order to show what is being accomplished by the use of L. 0. X., results will be shown from May to November, 1926, inclusive, and compared to the same period in 1925. No work was done in No. 1 pit during May, 1925, hence all figures are unduly low for this month.

Jan 2, 1927

By W. D. Robertson, Raymond C. Boettner

A study was made of the change in density during the first (transient) and second (linear) stages of the creep curve of polycrystalline copper as a function of 1) stress, 2) temperature, 3) plastic strain, 4) impurity and atmosphere effects, and 5) structure, including single crystals. Voids were not observed in single crystals strained 15 pct at 500°C, or in a polycrystal-line aggregate produced by recrystallizing a single crystal, within the limit of sensitivity, Ae/e = 1 x 10-4. It appears that voids are heterogeneously nucleated at grain boundaries by an insoluble phase, or phases, which can be removed by directional solidification. The principal controlling mechanism of void growth appears to be condensation of vacancies at grain boundaries. Vacancies are transported to a boundary and condense as a consequence of the tensile stress component across the boundary, which depends on the orientation and configuration of the boundary plane and on boundary shear across ledges and other irregularities. The ultimate source of vacancies is the free surface and diffusional transport is by way of the boundary plane. PREVIOUS investigations have dealt with the nucle-ation of voids at grain boundaries under creep condition~'-~ and with the connection between grain boundary voids and subsequent brittle fracture.5-7 Growth of voids during the creep process, particularly in the transient and linear stages of creep, has not been studied with the same intensity. Therefore, it seems pertinent to investigate the process of void growth with respect to the related creep curve, and the morphology of growing voids with respect to the structure.

Jan 1, 1962

` LAWRENCE ADDICKS, New York, N. Y.-We have really two competitive processes for the production of electrolytic zinc. In the process used at Great Falls, the ore is roasted and the calcines leached, leaving a residue which has to be smelted; in the other method, the ore is burned, the zinc and lead fumed off, and the condensed fumes are leached. I do not think that we can yet come to any decision as to which is the better way to attack the problem. Of course if we roast first and then leach, various substances remain in the calcines which may consume sulphuric acid; whereas if we do the burning first, we obtain simply the zinc and lead oxides, with considerable sulphate, in the fume, and there is no shortage of acid. It also depends partly on the complexity of the ore. The one that Mr. Hall is treating and the ore they are treating at Great Falls are not quite alike, but I think they are sufficiently similar to make a comparison of the two methods, working in competition, on different parts of the country, very interesting. C. E. SCHWARTZ, Miami, Okla.-Mr. Hall states that the Joplin conditions are not suitable for the manufacture of electrolytic zinc. When we speak of Joplin ore in general, we consider, of course, a 60-per cent: concentrate with comparatively low iron, but if a low-grade concentrate could be made from tailings and so-called chats, then the problem would be quite different. A Joplin ore is comparatively simple to treat electrolytically, and I believe the electrolytic process would open a field for the treatment of such ores as would not be ordinarily smeltable; that is,

Jan 1, 1918

By Fred P. Dewey

IN preparing material for the exhibit of the National Museum at the New Orleans Exposition in 1881, it was decided to attempt to photograph the interior of a coal-mine, in order to get a strictly truthful representation of a thick coal-seam, and to show incidentally the methods of mining. While we have many drawings, both mechanical and artistic, illustrating the subject, they are not satisfactory for these purposes, simply because they are drawings. Aside from this, much interest attaches to pictures of inaccessible places, and the enlarged copies (30 inches by 40 inches) of the photographs we succeeded in obtaining, have attracted a large amount of attention from the visitors to the Museum. The Kohinoor colliery, Shenandoah City, Pa., was selected as most suitable for the attempt, principally on account of the fine exposure of the Mammoth bed, and the comparatively level character of the workings, in that colliery. This is one of the many anthracite-mines of the Philadelphia and Reading Coal and Iron Company. A detailed section of the fiftyfoot or Mammoth bed in this colliery is as follows: Feet. Inches. 1 0 Clod. 1 7 0 Coal. 1 0 Slate. Top Split. 8 0 Coal. 1 6 Slate divider.* 6 0 Coal. 1 0 6 Slate. 2 6 Coal. 0 5 Slate. 1 8 Coal. 1 2 Charcoal. 5 0 coal. 1 0 Bone and Coal. „ „ Coal. [ Bottom Split. 0 6 Bone and Slate. 3 0 Coal. 0 10 Bone and coal. 1 2 Coal. 0 2 Bone. 4 4 Coal. 0 1 Bone. 0 8 Coal.

Jan 1, 1888

By J. Weijdema, D. N. Dietz

In the conventional underground combustion process (dry combustion) much heat is left behind in the swept formation and goes to rva.rte. Econonmy can be improved by heat recuperation through water injection. This is most advantageous if done at the earliest opportunity before much heat is dissiputed to cap and base rock. Water injected simultaneously with the air will flash to superheated steam, which passes through the combustion front together with the nitrogen from the air. A condensation front traveling up to three times as fast as the combustion front drives out the oil. In this type of wet combustion, the water evaporates before it reaches the combustion zone. The evaporation front travels more slowly than the combustion zone. If so much water is injected that the evaporation front overrun the combustion front, combustion in that spot will be quenched and some unburned fuel will be left behind. Air reacts with the oil farther down-stream where steam temperatures occur; at steam temperature, the air reacts rapidly with the oil. Velocity of the combustion front is increased thereby and is governed essentially by the water-injection rate. In the extreme case of high water-injection rate, a short heat wave of constant length is driven through the formation by water injection. Once this wave has been established, no more heat need be generated than that required to make up the heat losses from the short heat wave; a relatively low rate of air injection will suffice. The feasibility of partially quenched combustion has been confirmed in tube experiments. A heat wave at steam temperature is observed. Chemical analyses of flue gas indicate preferential burning of hydrogen while a carbonaceous residue is left in the formation. Introduction A disadvantage of so-called dry in situ combustion is that air-compression costs are rather high. An air consumption of about 400 std cu m/cu m (400 scf/cu ft) of formation swept is an accepted figure. This high consumption is mostly wasted since much heat is left behind in the depleted oil sand. Methods were investigated for recuperating as much as possible of the heat left behind. This paper deals only with basic principles and is confined mainly to one-dimen- sional flow without lateral heat losses; experiments were conducted in relatively narrow, well insulated tubes. If some water is injected with the air, it will turn to superheated steam in an evaporation front, which should travel behind the combustion front. The steam having passed the combustion front causes a steam drive by a condensation front that can travel faster than the combustion front. The latter needs to travel only part of the distance covered by the oil-displacing condensation front, and thus consumes less air. The water-air ratio would seem limited to that at which cold water overruns the combustion. This limitation was deliberately exceeded considerably in theory and experiments. It was found that combustion is then indeed quenched, but only locally. Farther downstream, the oxygen finds residual oil at steam temperature, which is suficiently high to ensure rapid oxidation. Thus, the combustion front uses only part of the available fuel because it is chased through the formation faster than its normal velocity. No heat is left behind. This new process is called "partially quenched combustion". At the upper limit of the water-air ratio, a small heat slug is moved through the formation by the flow of water and steam. Only a small flow of air is needed since it has only to generate sufficient heat to make up for the lateral heat losses of the short heat slug. Theory Although many factors complicate underground combustion, the processes will be presented in their simplest form. For this reason, one-dimensional flow without lateral heat losses is assumed. Heat conduction in the direction of flow also is disregarded. Under these conditions, dry combustion causes very high temperatures. The heat-carrying capacity of the gas stream is small. Heat generated by oxidation of a residual oil saturation is retained in the sand. The available fuel determines the air requirement and the temperature obtained. Accepting the often-mentioned air consumption of 400 std cu m/cu m (400 scf/cu ft) formation, we calculate a temperature of the swept sand of 1,200C (2,192F) (Fig, I). If water is injected at a modest rate with the air, it will flash to superheated steam upon contact with the heated sand. One cu m (35.31 cu ft) of hot formation will evaporate about 0.5 cu m (17.66 cu ft) of water, and thereafter will accommodate (at an estimated 0.80 saturation and an assumed 0.40 porosity) another 0.3 cu m (10.59 cu ft) of water in cold condition. As long as less than 0.5 + 0.3 = 0.8 cu m (28.25 cu ft) of water is injected for every 400 std cu m (14,125 scf) of air (water-

Jan 1, 1969

By David S. Butts

The high cost of energy has made many solution mining corporations turn from fuel consuming evaporators to solar energy and solar ponds. The generally held concept of a solar pond is an area enclosed by dikes into which brine is pumped, water evaporated by the sun, and the resulting salts scraped from the bottom of the pond. This paper will show that solar ponding is not simple. It is a science involving six main areas. These areas are (1) land conditions, (2) meteorology, (3) fresh water, (4) accessibility, (5) manpower and (6) mineral resources. Each area is discussed to identify important parameters that must be investigated before the viability of a solar pond complex can be established as a mineral recovery step.

Jan 1, 1985

By J. E. Berg

THE geology of the Coeur d'Alene mining district is so familiar to every one interested in mining that I will only note as an introduction that the main producers are mines whose orebodies lie in the Revett or Burke quartzites ; that the known orebodies in the eastern part of the district all lie north of the Osburn fault; that the Prichard formation is quite generally looked upon as being unfavorable for lead deposits ; that the monzonite intrusive mass extending north from Gem to Sunset Peak, and over into Cedar Creek divide, is considered to have been the prime agent in the crea-tion of our orebodies, and that diabase dikes are a quite common feature at most of the properties with which I am familiar. Some of the exceptions to these statements may be mentioned. The Interstate-Callahan mine is considered the exception disproving the alleged relation between large ore-deposits and the Prichard formation, but this property was primarily a zinc producer, with lead secondary, though of sufficient tonnage to be a valuable product. A second interesting occurrence in the Prichard worth calling to your attention is the Jack Waite property, on Tributary Creek, north of Murray. This vein lies at a low horizon in the Prichard forma-tion, and the ore differs essentially from others in the same horizon elsewhere in that it is a clean, medium to coarsely crystalline, lead ore carrying very little zinc, about one ounce silver to ten units lead, and is accom-panied by a clean quartz gangue or vein filling. I believe that quartz was the primary mineral in the fissure, and that the lead ore was deposited in the vein as a replacement of the quartz.

Jan 7, 1927

By W. G. Matteson

BENJAMIN L. MILLER, So. Bethlehem, Pa.-In discussing the question personally with Mr. Matteson I have found that he simply proposed this as a suggestion and he recognizes, as well as a great many other oil geologists and oil operators, that to put into practice such a suggestion would mean the overcoming of many difficulties. Yet perhaps it may be possible to overcome the various objections that may be offered. Undoubtedly one of the most serious objections is that of incomplete and inaccurate well records. Faulty records are worse than no records at all. Perhaps, however, definite instructions and insistence on their observation may remedy this defect after a time. THE CHAIRMAN (M. L. REQUA, San Francisco, Cal.).-This subject is a. very important one, but just how far the National Government can go in .taking action is a question: It involves, of course, the question of State rights. California, I .think, has done very well up to date and probably will do better in the future. The law that was passed at the session of the Legislature 2 years ago is working as satisfactorily as anything of that kind can work with so little experience to guide the framers of the statute. We recognize in California the vital necessity of conserving the oil of the State. We have come to the conclusion that there is not as much oil ,in California as we thought there was. In the month of December the State drew on its oil stocks to- the extent of 1,800,000 bbl. and I think that the January statistics will show probably as much more. There is more or less of a.: panic at the present time among the large marketing concerns regarding the question as to where they are going to get their oil for future requirements

Jan 4, 1917